interface PCI{
	void start();
	void stop();
}

class NetWorkCard implements PCI{
	public void start(){
		System.out.println("send....");
	}
	
	public void stop(){
		System.out.println("NetWork Stop");
	}
}

class SoundCard implements PCI{
	public void start(){
		System.out.println("Du Du...");
	}
	
	public void stop(){
		System.out.println("Sound stop");
	}
}

class MainBoard{
	public void usePCICard(PCI p){
		p.start();
		p.stop();
	}
}

public class Assembler{
	public static void main(String[] args){
		MainBoard mb = new MainBoard();
		NetWorkCard nc = new NetWorkCard();
		mb.usePCICard(nc);
		SoundCard sc = new SoundCard();
		mb.usePCICard(sc);
	}
}
